FIG 4.

Lung histopathology. HE-stained lung sections from control (sham-infected) mice or from those infected with the blood isolate (ST15/4495) or the ear isolate (ST15/9-47) at 6 h were examined by light microscopy. (A) Representative sections from each group are shown. Bar, 0.1 mm. Slides were also scored (blind) according the following 8-point scheme: congested capillaries (fine arrows) were scored 0 to 2; thickened alveolar wall (arrowheads) were scored 0 to 2; swollen cuboidal epithelial cells of the bronchioles (thick arrows) were scored 0 to 2; and secretions in the alveolar and bronchiole space (open arrows) were scored 0 to 2. (B) Data were examined with Student's unpaired two-tailed t test and are presented as mean ± SE for each group.